@article {2562,
	title = {Applications and limitations of U{\textendash}Th disequilibria systematics for determining ages of carbonate alteration minerals in peridotite},
	journal = {Chemical Geology},
	volume = {412},
	year = {2015},
	month = {Jan-09-2015},
	pages = {151 - 166},
	abstract = {238U{\textendash}234U{\textendash}230Th dating was conducted on carbonate alteration minerals in the peridotite layer of the Samail Ophiolite, Sultanate of Oman, in order to assess the applicability of U-series dating techniques to these types of Quaternary terrestrial carbonates and also to further constrain natural rates of carbonation of the peridotite. Due to their low U concentrations and relatively high Th/U ratios, Samail carbonates are challenging to date with the 230Th technique because of the sensitivity of ages to corrections for initial 230Th. Uncorrected 230Th ages for Ca-rich travertines are consistently older than previously obtained 14C ages. However, geologically reasonable initial 230Th corrections bring the two sets of ages into concordance. This age concordance suggests that the travertines are generally closed systems, adding a level of credence to the reliability of previously obtained 14C ages. In contrast, uncorrected 230Th ages for Mg-rich carbonate veins are generally younger than previously obtained 14C ages. These young ages are interpreted in terms of remobilization of hexavalent U, which is subsequently deposited as tetravalent U by reduced serpentinization fluids. Two Mg-rich carbonate veins sampled at a roadcut have near-equilibrium (230Th/238U) and (234U/238U) values, which indicate that these veins are > 375,000 years in age, consistent with their {\textquotedblleft}14C dead{\textquotedblright} (> 50,000 years BP) ages. The variable young and old ages for these Mg-rich carbonate veins indicate that carbonation of the peridotite layer of the Samail Ophiolite is an ongoing process and that there have been multiple generations of subsurface carbonate vein formation. Overall, this study provides insights into some of the challenges associated with applying U-series dating methods to Quaternary terrestrial carbonates, in particular carbonate alteration minerals in peridotites, and highlights some areas where there is room for improvement, such as obtaining better constraints on the isotopic composition of admixed detritus, and also some advantages, such as the ability to identify open system behavior not apparent from 14C dating and stable C and O isotopic analysis alone. 

},
	issn = {00092541},
	doi = {10.1016/j.chemgeo.2015.07.023},
	url = {http://linkinghub.elsevier.com/retrieve/pii/S0009254115003435},
	author = {Mervine, Evelyn M. and Sims, Kenneth W.W. and Humphris, Susan E. and Kelemen, Peter B.}
}
@article {47,
	title = {Carbonation rates of peridotite in the Samail Ophiolite, Sultanate of Oman, constrained through 14C dating and stable isotopes},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {126},
	year = {2014},
	pages = {371-397},
	abstract = {Detailed 14C dating as well as stable C and O isotope analyses were conducted on carbonates formed during alteration of the peridotite layer of the Samail Ophiolite, Sultanate of Oman. 14C results obtained in this and previous studies indicate that surface travertines range in age from modern to >45,000 yr BP, indicating long-term deposition and preservation. Travertine deposition rates in two localities were \~{}0.1 to 0.3 mm/yr between \~{}30,000 and 45,000 yr BP. Using an estimate of total travertine area, this would result in a maximum of \~{}1000 to 3000 m3/yr of travertine being deposited throughout the ophiolite during this time period. This travertine deposition would have sequestered a maximum of \~{}1 to 3 {\texttimes} 106 kg CO2/yr. Ca-rich carbonate veins that are associated with the surface travertine deposits have ages ranging from \~{}4000 to 36,000 yr BP (average: 15,000 yr BP). Mg-rich carbonate veins exposed in outcrops have ages ranging from \~{}8000 to 45,000 yr BP (average: 35,000 yr BP). Detailed sampling from numerous locations (3 locations in this study and 10 locations in the previous studies) indicates that no carbonate veins from the natural peridotite weathering surface are older than the \~{}50,000 yr BP dating limit of 14C. However, 14C dating of Mg-rich carbonate veins from three roadcut exposures (Qafeefah, Fanja, and Al-Wuqbah) indicates that a significant number of roadcut veins are 14C dead (>50,000 yr BP). A location weighted average indicates that \~{}40\% of veins sampled at the three roadcuts are 14C dead. An average including veins sampled at both roadcuts and outcrops indicates that overall \~{}8\% of Mg-rich carbonate veins are 14C dead. Mg-rich carbonate veins are estimated to sequester on the order of 107 kg CO2/yr throughout the ophiolite.},
	issn = {0016-7037},
	doi = {10.1016/j.gca.2013.11.007},
	url = {http://www.sciencedirect.com/science/article/pii/S0016703713006467},
	author = {Mervine, Evelyn M. and Humphris, Susan E. and Sims, Kenneth W. W. and Kelemen, Peter B. and W. J. Jenkins}
}
